Well, I hate to say it but it is either a new motor or rebuild the 383 that I have. I think I will rebuild...cheaper! 383 with 10.5 compression. I will change the heads to the new AFR 195,s and go with a vodoo 566/578" mechanical roller. Intake and carb will remain the same. Rpm air gap with a Barry Grant 750 speed demon. Msd ignition will light the candles. Right now I have about 450 horse using a hyd. cam with 108 centers, .480 lift. The motor makes me nervous for some reason. The heads, are aluminium, but have straight plugs..pain in the butt. How much horse do you think the new combo would be putting out, I would like around 500. I am also going to be switching from the M-21 to a tremac. I think with my 3.73 gears I should be able to get out of the way. Whatcha all think...oh yeah...I thought I was done!!